How important is sleep to protect against infection?
When people get too little sleep, it negatively affects their physical and mental health and overall performance. Adequate sleep is believed to be important for the immune system and defense against pathogens. However, experts have now attempted to clarify exactly how sleep influences certain immune functions in their new research work.
In their current study, the scientists at the German University of Tübingen and the University of Lübeck have shown a new mechanism by which our sleep promotes the immune system. The doctors published the results of their study in the English-language journal "Journal of Experimental Medicine".
Lack of sleep affects the functioning of the T cells
The team of experts around Dr. Luciana Besedovsky and Dr. Stoyan Dimitrov from the Tübingen Institute for Medical Psychology and Behavioral Neurobiology and Dr. Tanja Lange from the Lübeck Clinic for Rheumatology and Clinical Immunology was able to show on subjects of the study that the function of the so-called T cells was impaired after only three hours without sleep. These white blood cells usually have the task of fighting pathogens.
A group of subjects was not allowed to sleep
The doctors recruited subjects for a 24-hour experiment. The participants were divided into two different groups. A group of subjects was allowed to sleep at night for eight hours. The other group had to stay awake for the entire duration of the experiment. Blood was drawn from the participants at regular intervals during the 24 hours.
What is Adhesion?
The researchers were particularly interested in the binding strength of the T cells to a molecule called ICAM-1 (intercellular adhesion molecule-1), which enables them to attach to other cells. This process is also known as adhesion. T cells constantly circulate in the bloodstream and look for pathogens there. "Adhesion to other cells allows them to migrate in the body and, for example, dock onto infected cells in order to then eliminate them," explains study author Dr. Stoyan Dimitrov in a press release. If the subjects suffered from lack of sleep, this affected the ability of the T cells to adhere. Participants without sleep showed a significantly reduced ability of the T cells to adhere.
Blood plasma was also examined
To further investigate the influence of sleep on T cell function, participants from both groups also took plasma from the blood. There are various soluble substances in the plasma, such as hormones. This plasma was then applied to isolated T cells for a few minutes. If the plasma came from participants who had not slept, there was a significantly reduced ability to adhere compared to sleepy subjects, the doctors explain.
Suppression of T cell function could be reversed
The team was able to reverse this suppression of T cell function in another experiment. To do this, the experts blocked a certain class of receptors, the so-called Gαs-coupled receptors. The stress hormone adrenaline and prostaglandins also act via these receptors. These hormones play an important role in inflammation. "This shows that even with a short sleep deprivation, soluble substances activate these receptors and also impair the adhesion of the T cells," reports the study author Dr. Luciana Besedovsky. Some of the soluble molecules that bind to this class of receptors, such as adrenaline, prostaglandins and the messenger adenosine, severely impair adhesion when applied directly to the T cells. In some pathological conditions, the same values show increased values, for example in chronic stress or cancer.
Three hours without sleep already reduce the function of immune cells
“This means that our findings are also of clinical relevance outside of sleep research. You could explain why the immune system is suppressed in some diseases, ”reports Dr. Tanja Lange. “Just three hours without sleep are enough to reduce the function of important immune cells. Our results show a possible, basic mechanism through which sleep supports us in our daily fight against infections, Luciana Besedovsky added. (as)